1. Inheritance
AOS

2. VCAA - Study Design inheritance:
– the nature of chromosomes, alleles, genotype and phenotype
– the causes of phenotypic variation: mutations; recombination of parental alleles in sexual reproduction; polygenes; and interactions of environmental factors with genes
– continuous and discontinuous variation
– patterns of inheritance involving the monohybrid cross: dominance; recessiveness; co-dominance; multiple alleles – dihybrid crosses as independent or linked – pedigree analysis: autosomal and sex-linked inheritance; use of the test cross.

3. Variation
Variation, the small differences that exist between individuals, can be described as being either be;
discontinuous
continuous

4. Continuous & Discontinuous Variation
that has no limit on the value that can occur within a population.
A line graph is used to represent continuous variation. Some examples are height, weight, intelligence, VCAA scores (don’t get me started!!)

5. Discontinuous Variation
individuals fall into a number of distinct classes or categories, and is based on features that cannot be measured across a complete range.

7. What is a Chromosome? Chromosome is the highly condensed form of DNA
Wrapped around histone proteins
Wrapped into chromatin fiber
Condensed during prophase into the familiar shape
Humans have 22 autosomal pairs
And one pair of sex chromosomes

9. Things to remember… Homologous chromosomes are not identical
Can have different alleles of genes
Sister chromatids are identical
Form as cells go through S phase (replication)
Attached to each other by centromere
Until Anaphase of Mitosis
Once separated each is again referred
to as a chromosome

10. Alleles
Each of two or more alternative forms of a gene that arise by mutation and are found at the same place (loci) on a chromosome

11. Genotype & Phenotype Genotype
the set of genes in our DNA which is responsible for a particular trait.
Phenotype
is the physical expression, or characteristics, of that trait

12. Remember Genotype cannot be changed (generally)
Phenotype is affected by the Environment

13. Variations - Phenotype
Variation in the phenotype is caused either by the environment, by genetics, or by a combination of the two
Meiosis and sexual reproduction introduces variation
Independent assortment of the parental chromosomes;
Crossing-over during Prophase I
The random fertilisation that forms the zygote.

14. Mutations Point - single base Frame - gene (more than one base)
Chromosome - structure

15. Mutations

16. Chromosomal Mutations
5 types of mutations can occur;Five t
Inversion,
Translocation, Click, watch, answer
Nondisjunction,
Duplication,
Deletion

17. Gene/Nucleotide Mutations
–Point Mutations
–Substitutions
–Insertions
–Deletions
–Frameshift
Click and GO!!!!

18. Patterns of Inheritance
One man and his peas

19. ……….and then came the flies
One man and his peas……
Terms you need to know;
Genotype
Phenotype
Homozygous
Heterozygous
Monohybrid
Dihybrid
……….and then came the flies

20. Genetics 101 Genetics use letters to represent alleles.
uppercase letters represent dominant alleles;
lower case represent recessive alleles.
An individual’s genotype is is expressed with one letter for each allele.
An example, the gene for plant height results in tall or dwarf (short) plants.
The allele for tall plant is dominant and is represented by upper case T.
The allele for dwarf plant is recessive and assigned a lower case t.
Possible genotypes are homozygous dominant ( TT) and heterozygous dominant (Tt) which gives a tall phenotype and homozygous recessive (tt) which presents a short phenotype.

21. Make sure we got this! TT Tt Rr rr rc

22. Assigning alleles
Do not use letters that are similar shape when they are Capital and Lower case;
GOOD
Rr, Tt, Bb, Aa
BAD
Ww, Ss, Pp

23. Punnets and Probability

24. PUNNETS

25. MONOHYBRID CROSS

26. Parental F1 F2
YOUR GO!

27. Two traits – Dihybrid Cross
Homozygous - Black fur: Long Tail BBTT
Heterozygous - Black fur: Long Tail BbTt
Homozygous - White fur: Short Tail bbtt

28. But first the rules

29. Rules

30. Two traits – Dihybrid Cross
Homozygous - Black fur: Long Tail BBTT
Heterozygous - Black fur: Long Tail BbTt
Homozygous - White fur: Short Tail bbtt

31. Practice time
Do Answer the questions

32. Test Cross

33. Linked Genes
Some genes do not assort independently of each other; but rather are inherited together.
They are on the same chromosome and are generally inherited together.
It is possible to measure the relative position of various linked genes by comparing the ratio of the parental genotypes to recombined genotypes.

34. Sex linked/X linked
A special type of monohybrid inheritance is called sex linkage.
Genes carried on either of the chromosomes responsible for sex (X or Y) are said to be sex-linked.

35. X linked dominant
In the case of X linked dominant traits the trait is more common in females than X linked recessive traits.
A father will always pass such a trait to his daughters.
A heterozygous mother will have a 50% chance of passing the trait to all her children regardless of sex.
Hemophillia (H = normal: h = disease)
Mum XHXh Dad XHY- (Mum is a carrier)
Mother

36. X linked recessive Hemophilia (H = normal: h = disease)
Mum XHXh Dad XhY-
Father is affected and mum is a carrier

37. Pedigree Charts Autosomal Dominant Autosomal Recessive
X-linked Dominant
X-linked Recessive

38. Autosomal Dominant